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By C. R. Bennett

The first phase in the design, development and implementation of a comprehensive computational model of a copper stockpile leach process is presented. The model accounts for transport phenomena through the stockpile, reaction kinetics for the important mineral species, oxygen and bacterial effects on the leach reactions, plus heat, energy and acid balances for the overall leach process. The paper describes the formulation of the leach process model and its implementation in PHYSICA+, a computational fluid dynamic (CFD) software environment. The model draws on a number of phenomena to represent the competing physical and chemical features active in the process model. The phenomena are essentially represented by a three-phase (solid-liquid-gas) multi-component transport system; novel algorithms and procedures are required to solve the model equations, including a methodology for dealing with multiple chemical species with different reaction rates in ore represented by multiple particle size fractions. Some initial validation results and application simulations are shown to illustrate the potential of the model.

Jan 1, 2003

By Helen Shang, Jianjun He

In nickel and copper production, sulfur dioxide (SO2) is generated during mineral smelting. Emission of sulfur dioxide into the atmosphere causes serious health and environment issues. Sulfuric acid plants, which convert the harmful SO2 gas to commercially useful sulfuric acid product, ensures safe and environmentally sound smelter operations. The sulfuric acid plant is mainly composed of a SO2 to SO3 converter, a series of heat exchangers and SO3 absorption towers. The SO2 converter is crucial for minimizing SO2 emission in a smelter. In this paper, steady state and dynamic modelling are carried out for the converter using mole and energy conservations. Simulations are performed to investigate the effect of feed conditions on SO2 conversion. The developed model represents an important component for modelling the acid plant in a smelter and is expected to provide a fundamental tool for the future optimization and control development.

Jan 1, 2014

By F. G. Tahmoush, N. J. Grant, E. P. Abrahamson

The effect of grain size on the brittle -ductile transition temperature of pure iron and three dilute Fe-W alloys has been investigated by slow bend tests. The brittle-ductile transition temperature for pure iron increased with increasing grain sizes from 8000 to 500 grains per sq mm where the transition temperature then decreased with further increase in grain size. The dilute additions of tungsten lowered the transition temperature for fine grain sizes, suppressed a reversal of the curve in the coarse grained portion, and raised the transition temperature for this region. The frequency of twin occurrence increased with increasing grain size and decreasing temperature. The object of the present investigation was to re-examine the effect of grain size on the brittle -ductile transition of pure iron and several dilute Fe-W alloys. Current literature normally presents a simple relationship between grain size and the brittle-ductile transition temperature, namely, that the transition temperature increases with increasing grain size. Heslop and etch' have studied the transition temperature of mild steel by V-notch Charpy impact tests for the grain size range between 200 and 6000 grains per sq mm. The result was a linear plot of In 1-1/2 vs brittle-ductile transition temperature, where 1 is the grain diameter. Recent experiments by sipos2 revealed the possibility of a reversal in the slope of the grain size vs transition temperature plot for pure iron; however, his investigation was limited in scope, and the data obtained were insufficient to permit a definitive curve. The present investigation was undertaken in an effort to confirm or extend the grain size effect observed in iron by Sipos. PROCEDURE All alloys were vacuum induction melted, using 99.95 pct Fe containing 0.03 pct 0 and 0.004 pct C. Four ingots were made, ranging from pure iron to iron with 0.035 pct W. The chemical composition of each alloy, after processing, is given in Table I. The four alloys were prepared as 45 lb heats and cast into 4 in. diam by 16 in. molds. They were then extruded into 3/4 in. rods at 1800oF. Specimens for chemical analysis, taken from various positions along the rods, revealed no variation in tungsten content along the length. The extruded rods were reduced to 0.156 in. diam stock by a series of cold swaging operations involving intermediate vacuum annealing treatments. This procedure yielded a final cold reduction in area ranging from 10 to 90 pct. The swaged rods were chemically cleaned, cold pressed to a cross section of 0.10 by 0.18 by 1.0 in. long (2.54 by 4.73 by 25 mm). The specimens were wrapped in iron foil and vacuum sealed (10-4 mm Hg) in quartz. Various heat treatments at temperatures from 700" to 1300oC were utilized to produce grain sizes from 8000 to 1 grain per sq mm. Grain sizes were determined by measuring the average area of grains in a polished section. In specimens with grain size greater than 20 grains per sq mm, the total number of grains in the cross section was counted and then divided by the area to yield grains per sq mm. Grain size was measured both for longitudinal and transverse cross sections. The average of the two measurements was plotted vs transition temperature. An Instron Table Model testing machine was used to determine the transition temperature of specimens tested in three point horizontal bending. The specimen was supported by two 1/4 in. dowels one in. apart. Bending was accomplished with a push rod, the end of which had an 1/8 in. radius. The head speed was 50 in. per min. Temperatures were established through the use

Jan 1, 1963

By D. Harker, W. E. Seymour

CERTAIN alloys of iron and nickel, when rolled and annealed, possess a preferred crystal orientation: (001) in the rolling plane and [loo] in the rolling direction, when recrystallized at 850" to 1050°C after approximately 98 pct cold reduction. Since the preferred orientation makes a direction of easiest magnetization coincide with the rolling direction, these alloys, especially a 50 pct iron in nickel alloy, have found wide application in the electrical industry' for choke coils and special types of transformers. The rate of the recrystallization reaction was studied at temperatures ranging from 500° to 600°C. The heat of activation for the reaction was calculated from the observed rates, and crystal orientation determinations were made before and after re-crystallization. A vacuum melted iron-nickel alloy* analyzing 49.6 pct nickel, 0.018 pct carbon, and 0.30 pct manganese was used for the experiments. The alloy was cold-rolled 98 pct into strips 1/2 in. wide by 0.002 in. thick. Specimens 1 in. long were sealed under a vacuum (approximately 10-8 mm Hg) in 1/2 in. ID pyrex glass tubes. For heat treatment these tubes were fastened to Nicrohm wires and submerged in a molten salt bath controlled to ±2°C. (The maximum measurement error was within 3°C.) The time at temperature was varied logarithmically from one sample to another, and runs were made at 500°, 525", 550" and 575°C. A molten lead bath was used for a run at 600°C which was controlled to the same accuracy. To determine the extent of recrystallization after a particular time at a given temperature, a method was used suggested by the work of Decker, Asp, and Harker.3,4 This method employs an X-ray spectrometer whereby X rays are diffracted from crystallites whose diffracting atom planes are parallel to the rolling plane of the specimen. The intensities of the diffracted rays are measured by a Geiger counter. The counter can be rotated through a range of angle, and can be motor driven through this range at a speed of 2" per min. The measured intensities are plotted vs. angle by a potentiometer recorder. In a 50 pct iron-nickel alloy it was found that only (200) reflections were obtained from the rolling plane with recrystallized material, and that only (220) reflections were obtained from the rolling plane with unrecrystallized material. No other reflections were obtained under these conditions over a range of Bragg angle of 0 to 45" using either type of specimen. As a consequence, the intensity of the (200) reflections from the rolling plane was taken to indicate the amount of recrystallized ma-terial present in a specimen, and the corresponding intensity of the (220) reflections was taken to indicate the amount of unrecrystallized material present. To insure flatness and proper alignment of the reflecting specimen in the spectrometer, the sample was laid in a slot 1/2 in. wide x 0.001 in. deep which was machined in a 3/4x2x1/2 in. steel carrier. The specimen then was taped down with cellophane tape. This steel cradle was mounted vertically in the specimen holder of the spectrometer so that the bottom edge of the carrier rested against a horizontal shoulder. Intensity data used in plotting the percent of recrystallized material vs. time at temperature were obtained by directly counting the diffracted beam of nickel filtered copper Ka radiation used throughout the work. The X-ray spectrometer was employed also in obtaining pole figure data to be used for orientation determinations. At the beginning of this investigation a transmission pole figure holder was used." As a thickness of 0.002 in. of this alloy was found to be opaque to the copper Ka radiation, it was necessary to reduce the thickness of the pole figure specimen. A cold-worked sample was etched in a 50 pct HCl solution for 5 min and was found to transmit a

Jan 1, 1951

By V. Sheikhzadeh, M. Saghaeian, N. Esmaeili, R. Hejazi, A. D. Ahmadabadi

The main challenges in most low grade iron ore deposits are finding the optimum flowsheet for beneficiation to achieve a final concentrate from both technical and economic viewpoints. Dry preconcentration techniques are being used to assist in reducing the amount of ROM feed to the plant. In this paper the benefits of utilising a dry cobbing magnetic separation technique for upgrading the product of HPGR in a closed circuit with dry screen 4 and 1.4 mm by performing a pilot scale test work was investigated. The experimental test work was done on two sample types of Yogi BIF magnetite iron ore located in Western Australia. Prior to magnetic separation studies, detailed characterisation of the feed materials including physical, chemical, mineralogical and magnetic properties were carried out. Furthermore, the effects of process parameters: drum rotation speed (1.5, 2.5 and 3.5 m/s), magnetic field intensity (1100 and 3800 gauss) and feed size (minus 4 and 1.4 mm) were investigated. The results revealed that sample type1 with 33.90% Fe could be upgraded to 41.51% Fe by using a stage of 1100 gauss dry magnetic separator with 69.12% weight recovery and 84.36% Fe recovery at a size of 4 mm. Also for sample type2, it is possible to increase Fe grade from 29.84% to above 36.68% with 75.58% weight recovery and 90.32% Fe recovery by applying one stage of 1100 gauss dry magnetic separator to a 4 mm size sample. Keywords: Banded iron formation (BIF), pre-concentration, dry cobbing technique, magnetic separator

Jan 1, 2020

By Wendell S. Williams

Single crystals of TIC doped with boron at high temperat~ires develop second-phase inclusions. The inclusions are in the form of lamellae lying parallel to {l 11 } planes of the Tic matrix and can be vevealed by etching [100] cleavage faces of the boron-doped Tic crystals. measurements of the critical resolved shear stress. t, of TIC crystals containing such inclusions showed that the ropid drop in t wilh increasing temperatu.ve found for pure Tic was greatly reduced. At 1600°C, the inclusion containing crystals had a value of t five limes that of pure Tic. The hardening effect also was found to inhibit hot pressing of TiC powders containing boron impurity. Thermochemical and crys-tallographic arguments suggest that the inclusions are TiB2. The boron content of the hardened carbide is a few tenths of 1 pct. TITANIUM carbide is noted for its high room-temperature hardness. However, measurements of the critical resolved shear stress, T, of single crystals of Tic at high temperatures have shown that t decreases exponentially with increasing temperature.' This temperature dependence of t is attributed to thermally activated dislocation mobility limited by a large Peierls stress.' In turn, this large Peierls stress is believed to be a consequence of strong co-valent and ionic binding in Tic. The rapid drop in 7 with increasing temperature, characteristic of pure Tic, is lessened by the introduction of second-phase inclusions. Exposure of Tic to boron at high temperatures produces such inclusions. A report of the influence of boron on t in Tic is presented, followed by a discussion of the nature and formation of boron-containing inclusions in Tic which are believed to be responsible for the hardening effect. I) CRITICAL RESOLVED SHEAR STRESS OF BORON-DOPED Tic CRYSTALS Tic single crystal boules grown by Union Carbide Corp., Linde Division, were doped with boron by placing them in a carbon crucible packed with boron powder and heating in a vacuum furnace to 2000°C for 1 hr. Samples 1 by 1 by 3 mm were cleaved from these doped boules. High-temperature compression tests' were made on these samples to determine the critical resolved shear stress as a function of temperature . The rapid drop in critical resolved shear stress found for pure Tic crystals' did not occur: tests indicated that the boron-doped crystals at 1600°C had values of T equal to those of pure Tic crystals heated to only 1100°C, Fig. 1. No difference in the shape of the individual stress-strain curves was produced by the boron doping, but the stress scale was multiplied by a large factor. The hardening effect of boron in Tic probably extends to temperatures lower than those used in the present work (1100°C minimum). At room temperature, however, the influence of boron is difficult to determine because the stress required for gross plastic flow in pure Tic is SO high that in practice fracture cccurs first. Microhardness is the only test that can give an indication of the yield stress in Tic at room temperature. such measurements were made5 on boron-doped Tic; the matrix had a hardness value

Jan 1, 1967

By C. H. Samans, G. F. Tisinai, J. K. Stanley

The times at which the first detectable amount of a phase forms at temperatures between 900° and 1800°F were determined. Both X-ray diffraction and metallography were used to detect a in highly strained filings; metallography alone to detect it in annealed bulk samples of six different types of stainless steels. The a phase was found to form in accordance with the C-type reaction curve in both austenitic and ferritic alloys. In filings of types 304, 347, and 446, a formed in a few hours, and in types 316, 309, and 310, it formed in a matter of minutes at temperatures corresponding to the knee of the C-curve. Only in the bulk type 309 steel, after 500 hr, and in the bulk type 310 steel, after as short a time as 25 hr at temperature, was n detected; in both instances at approximately the same optimum temperature as in the filings. The annealing temperature affected a phase nucleation only for the filings of type 304 and 347 steels, and for the bulk samples of type 309 and 310 steels. KNOWLEDGE of both the rate of nucleation and the rate of growth of the new phase is required for a complete description of metallurgical rate phenomena. However, data on the time for nucleation alone may frequently be useful in evaluating the tendency of commercial stainlcss steels to form s under various conditions. Very little correlated information of this type is available in the literature. Shortsleeve and Nicholson' indicate that s forms in ferritic 24, 27 and 30 pet Cr steels according to a C-type of reaction curve, and Emmanuel's' data for austenitic type 310 steel also suggest this type of solid state reaction. In addition, significant, though fragmentary, information has been given by Binder, Dulis and Smith,4 Payson and Savage,.; Guarneri, Miller, and Vawter,8 rerichs and Clark,7 Wilder,5 Lismer, Pryce, and Andrews,' Smith, Dulis, and Link,10 Dulis, Smith, and Houston," and Henry, Cordovi, and Fischer." The bearing of these data on this work is covered in the discussion. The purpose of this paper is to present such correlated data on s formation in AISI type 304 (18 pct Cr-8 pet Ni), 347 (18 pet Cr-10 pet Ni-Cb), 316 (18 pet Cr-12 pet Ni-2 pet Mo), 309 (25 pet Cr-12 pet Ni), 310 (25 pet Cr-20 pet Ni), and 446 (27 pet Cr) stainless steels. Materials and Test Methods X-ray diffraction and metallographic methods were used to determine the first appearance of the s phase in cold worked filings and in annealed bulk samples of seven steels, under various combinations of time and temperature. The rate of growth of the s particles was not determined. Commercial heats of six AISI steels and a low carbon laboratory experimental heat containing about 28 pet Cr were studied. Analyses are given in Table I. Because cold work greatly accelerates the nucleation of s particles, the relative rates of s nucleation in mechanically strained samples, i.e., filings through 120 mesh, were determined for direct comparison with those in annealed bulk alloys of the same composition.

Jan 1, 1957

By Robert D. Pehlke, Weldon L. Daines

The reduction of manganese oxide from a basic slag by silicon dissolved in liquid iron at steelmaking temperatures was studied to determine the rate-controlling step for the process. The experiments were carried out under an argon atmosphere in a resistance-heated vertical-tube furnace. The two liquid phases, slag and metal, were held in zirconia crucibles. Sampling and chemical analysis of the slag phase led to time-concentration curves for the system. Results obtained by varying parameters such as temperature, stirring rate, concentration, and melt geometry defined the limiting reaction mechanism. The reduction of manganese oxide by silicon is a fast reaction and reached equilibrium within 90 min. The rate of stirring has a marked effect on the reaction rate, while, on the other hand, the effect of temperature is very small. This identifies the rate-controlling step as diffusion rather than interfaciul chemical reaction. The variation of other parameters revealed that a) diffusion of manganese in the iron phase is the slow step, b) the value of D/6 for manganese in iron at 1550°C is 7x 10-4 cm per sec, c) the energy of activation for the apparent rate constant is 7 kcal per mole, and d) increasing the amount of silicon in the iron decreases the diffusion coefficient of manganese. THE equilibrium relations pertinent to the reduction of manganese oxide from a steelmaking slag by silicon dissolved in liquid iron have been studied, but little is known about the mechanisms that control the rate of the process. The purpose of the present investigation was to study the rate of reduction by silicon and to determine the rate-limiting step. The effects of stirring rate, temperature, composition, and melt geometry were investigated as a means of identifying the controlling step. On the laboratory scale, relatively little work has been done in the area of slag-metal kinetics, primarily because of the problems confronted in attempting to contain liquid slags and metals in laboratory crucibles at steelmaking temperatures. Since graphite is an ideal material for a crucible, several investigations have been carried out on the reduction of various oxides from a slag by carbon in graphite-saturated iron and on the transfer of sulfur between a slag and graphite-saturated iron. Most of this work has been performed in induction furnaces. Studies where the container was not graphite are extremely limited. A single kinetic study of manganese transfer between molten iron and basic slags was carried out by Sano, Shiomi, and Matsushita.' These investigators prepared calcium oxide and titanium oxide crucibles to contain the two-phase system. Only a few experiments were carried out and the results had to be treated qualitatively. Despite the paucity of kinetic data, a large quantity of information is available in the literature concerning the thermodynamics2-12 and physical properties'3-21 of the slags containing manganese oxide and the dilute liquid iron alloys containing manganese and silicon which were involved in this research program. EXPERIMENTAL METHOD A vertical-tube resistance-heated furnace was used in this investigation to study the slag-metal reaction Although most previous slag-metal studies were carried out in induction furnaces, a resistance furnace has several advantages including better control of temperature and stirring rate. Hence, a resistance furnace was selected for this study, and its design is shown schematically in Fig. 1. Slip-cast, fine-grained, low-porosity, lime-stabilized cubic zirconia crucibles were used for the kinetic experiments. The crucibles were 4 1/2 in. high and 2 1/8 in. OD with a 1/16-in. wall. The crucibles were only slightly

Jan 1, 1969

By B. K. Chakrabarti

Modeling and a screening design of experiment (DOE) was performed with the process variables to identify the greatest effect of variables on the response quality in the dead burning of magnesite refractory in a rotary kiln. Among various interdependent variable factors, the design variables chosen were raw magnesite (RM) feed rate, kiln rotation time i,e, seconds per rotation(SPM) and burning zone temperature (BZT). The response variables chosen were exit gas temperature and density of dead burnt magnesite(DBM). ANOVA and normal plots were used to evaluate the effects.This work had enabled to correlate the BZT, RPM, RM feed with the exit gas temp and density of magnesite produced. The result opens up an avenue to look into the optimum region of operations within the ranges of variables considered in order to conserve energy and to minimize the exhaust gas temperature and to maximize the density of the DBM produced

Jan 1, 2015

By C. Gary Reiness

A safety glass eyepiece which had been repeatedly exposed to mine environment over a number of years was studied to determine some of its optical properties. In the regions from 385 to 400 mµ and from 625 to 760 mµ, the transmittance was less than the 89 percent required by the American Standard Safety Code for Head, Eye, and Respiratory Protection. From 200 to 320 mµ the relative transmittance of two parts of the eyepiece was found to vary widely, having a maximum of 38 percent difference at 315 mµ. Irradiation of the glass by ultraviolet light caused enhanced absorption in the range from 200 to 1,200 mµ. There was a time-dependent increase of 1016 color centers per cubic centimeter throughout this range after 36.5 hours of irradiation. The rate-of-growth curve for the optical density, at 243.5 mµ and 23° C, was resolved into linear and saturable components, indicating zero order and first order

Jan 1, 1968

Material sampling theory is well established in mineral process monitoring, improvement and control. It has been much enhanced by fundamental contributions due to Gy. When GyÆs sampling theory is applied to sampling inspection and monitoring, it provides estimates of average quality or extent of contamination. It also provides estimates of uncertainty, but these often ignore uncertainty in estimated variograms or other measures of variability. Risk assessment is often an implied task in sampling inspection and quality monitoring. A valid technique of risk assessment needs to take into account the uncertainty in the variational measures themselves. Standard statistical tolerance limit calculations which do take such uncertainty into account can be adapted to develop a technique for handling uncertainty in variational measures such as the variogram. Data from a published example is used to illustrate the technique.

Jan 1, 2005

By Mark C. J

Since the commissioning of the BHAS Copper Plant in 1984 the copper electrowinning operations have not fully met expectations. During 1988, a laboratory scale electrowinning unit was constructed to enable an investigation of the effects of process parameters on copper cathode deposition and quality. The process parameters investigated were copper concentration, acid concentration, current density, electrolyte temperature, electrolyte flow, electrolyte impurities and electrolyte additives. The findings of this research program indicate that there is an optimum cathode deposition morphology which results in good quality copper deposits which have improved stripping characteristics. All of the process variables investigated influenced the copper deposition and therefore it was necessary to delineate a suitable operating envelope for the copper electrowinning. As a result new standard operating parameters in electrowinning have been implemented which has enabled the production of higher quality copper cathodes with improved stripping characteristics.

Jan 1, 1989

In making any attempts to determine the depositional environments in which coal seams accumulated it would be useful to establish whether there is a pattern, or patterns, of development which the majority of the seams have followed. To this end, the distribution of types of coal seam sequences found in the standard petrographic profiles of about a hundred Australian coal seams of Permian and Triassic age has been examined statistically, using the "chi square test" with the limiting probability set at O·Gl.Results indicate that non-random conditions have probably prevailed during the deposition of most of the seams. More samples are needed for conclusive results.The plants, or some other internal feature of the swamp environment, have been the important controlling factor in the development of the seam sequences.Comparison has been made with some British Carboniferous coals.

Jan 1, 1972

By J. E. deMasi

Over the past 12 years, Exxon Coal U.S.A., Inc. has shipped over 150 million tons of coal from two mines, Rawhide and Caballo, located in the Gillette, Wyoming, area. These mines are operated by The Carter Mining Company, a division of Exxon Coal. Shipments have moved to more than 25 electric utility plants in the west, midwest, southwest, and south. The customer plants have represented a wide variety of configurations, sizes. design criteria, emission standards, and operations in different parts of the country. We have learned a great deal about the performance of Gillette area coals in utility power plants during this period. This paper covers some of the highlights of Exxon's experience with these coals in customer plants. I will focus specifically on things mining engineers may be able to do to make the product better for the customer's use.

Jan 1, 1989

By David C. McLean, Peter Penner, Martin de G. Salter

The Rogers Pass Project for C.P. Rail includes a 14.7 km tunnel and an 8.5m diameter concrete lined ventilation shaft to a depth of about 335m. The shaft collar is in bouldered water bearing glacial till to a depth of about 95m. Initial excavation in the overburden was with the aid of dewatering wells. When ground support problems arose the excavation was completed by a two stage freeze programme. Freeze holes were drilled from the shaft bottom. This most unusual method was successful in overcoming the difficulties safely and efficiently. The remainder of the shaft was sunk and lined conventionally. Finally, a central dividing wall was poured by jump forming from the bottom up. The wall was completed to a high standard at up to about 20 vertical metres per day.

Jan 1, 1989

By Guray Kaya

Boron minerals are widely employed in various fields such as ceramic, glass, cement, metallurgy, etc. Although boron deposits of the world are limited, the production level of boron-based products is continuously increased. Turkiye possesses approximately 73 % of total world boron resources. Etibor Kirka Borax Company of Turkiye produces tincal concentrates and borax pentahydrates. During such productions considerable amounts of concentration and derivation wastes appear. Having considered the increased rate of production it is quite obvious that the level of relevant wastes will also be raised. With this study it was aimed to utilize these wastes in roof tile and brick bodies and to convert them into a form environmentally and human friendly. Newly produced products were undergone to several standard tests for the determination of their shrinkage, water absorption, strength values and coloring parameters. Additionally, micro structural studies were conducted.

Jan 1, 2006

By E. J. McKee

THE area discussed lies south of Canadian River in Hutchinson County, Texas, covering approximately 10 m. east and west and 4 m. north and south. Development is carried on in the manner usual in standard tool operations. No outstanding divergence from the usual methods is necessary as wells are completed in 35 to 55 days to approximately 3000 ft. Most of the time is lost in the upper part of the hole and is usually caused in driving pipe of larger sizes. After approximately 1500 ft., little trouble occurs. A comparison of 13 contractors drilling for Phillips Petroleum Co. gave the following averages: Drilling time from 32 to 63 days with a daily footage of from 49 to 87 ft. per day. The rigs furnished are National turnbuckle type with 6-in. irons and steel wheels.

Jan 11, 1926

By Alan K. Burton

The individuality of off-highway trucks is largely determined by a number of truck components that include beds, frames, and suspensions. With the exception of tires, these features are generally standard equipment and the mine operator gets "what comes with the truck." With the advent of larger trucks, more complicated haul profiles, and sophisticated production control systems, a new truck support-component industry is rapidly appearing. The impact of the new options for off-highway trucks can be significant in terms of future fleet performance. Innovations include "Mesabi" radiator cores that reportedly offer greater engine temperature control; load indicators that insure proper truck loading at the shovel; and digital communication systems that signal truck status in the haulage cycle. An understanding of tires, brakes, and newly introduced support components is necessary before an optimum choice of truck can be made

Jan 11, 1975

Any engineering firm hoping to do business in the modern world must understand-and take into account-the social and economic realities of client, country, culture, and community. If these considerations are ignored, any large-scale international development project is doomed to failure even before it begins. In this changing world, the distinctions between `developed', `developing', and `less developed' nations are more and more blurred. The so-called `less-developed' and `developing' nations are rapidly acquiring technology, an educated man- agerial and technical class, manufacturing capa- bilities, a growing spectrum of developed financial and raw materials resources, and a broad range of labour skills. These nations are establishing themselves as an integral part of the modern world, on an equal footing with other nations and with justifiable expectations for an ever higher standard of living and an ever better quality of Life.

Jan 1, 1978

A method, based on the macroscopic population balance equation allowing the dynamic simulation of a multistage adsorption plant given an arbitrary rate expression, is described. The partial differential equations resulting from this method are simplified using the method of characteristics. The simplified equations can then be solved using standard ODE integration techniques. The procedure is illustrated by means of data typical of a CIP application. Requirements for data structures which allow the incorporation of the carbon-in-pulp (CIP) model (and other unit models) into a general metallurgical simulator are described. Based on these considerations, it is concluded that more generality in the description of distributed quantities such as loading and particle size is provided by the use of mass density at fixed class boundaries, rather than discrete masses within fixed classes as has hitherto been used by ore-dressing simulators.

Jan 1, 1987